While the study of PBHs formation and the generation of primordial GW has been actively pursued over recent years in different inflationary models, there has been not so many studies in the context of warm inflation. In standard, cold inflationary scenarios, inflaton interactions play no role neither in the slow-roll dynamics not in the generation of the primordial spectrum; on the contrary in warm inflation, those interactions can lead to the partial dissipation of the inflaton energy density into radiation already during inflation [1]}, [2]}, [3]}. The presence of a subdominant thermal bath can modify the dynamics both at the background and the perturbation level. When dissipation dominates over the Hubble friction term, the motion of the inflaton field will be further slow-down, enlarging the duration of inflation. On one hand slow-roll conditions are easier to fulfil, and in particular the inflaton mass can be closer to the Hubble parameter during inflation, relaxing the so-called “\(\eta \) ”-problem [4]}, [5]}. And in single-field models of inflation like chaotic-like ones, the last 60 efolds of inflation can take place at smaller values of the inflaton energy density and the Hubble parameter \(H\) , meaning a smaller value of the primordial tensor perturbations and the tensor-to-scalar ratio. Most importantly, the presence of the thermal bath means that inflaton perturbations acquire now a thermal component on top of the standard vacuum one, with implications also for the properties of the scalar primordial spectrum. Models that are excluded by observations in their simpler cold inflation version, like quartic and quadratic chaotic models, are perfectly compatible with Planck data in their warm version [6]}.
